An Open Social application is essentially a Javascript program that
runs in a “container” which provides the “Open Social Javascript API”
via two Javascript namespaces: “opensocial” and “gadgets.

Google’s “Gadgets” are a kind of standardized applet. They are specified by an XML file which provides rendering.A gadget server needs to provide this “rendering” code to turn gadgets
into executable Javascript code and then to
run them.